He is one of the top slayers of the Demon Slayer Corps, the 「Mist Hashira」.
Muichiro is a short young man of light complexion with long, straight hair of a black color that fades to turquoise as it approaches his waist.
He has a lop rabbit kind of hairstyle. It is not clear whether those are two-side-up twintails or just a kink in the hair.
He also possesses large, empty-looking, mint-green eyes.

According to Tengen Uzui, he is very talented and able to upgrade to Hashira in just two months after he first touched a sword.

To restore his sword outworn in fighting Upper Moon Six, Tanjito visited the Swordsmith Village, during the same period Muichiro happened to be staying in the village for special swordsmanship training.

Personality

Muichiro is a carefree kind of person and seems to constantly wander off in thought. During the whole「Trial by Hashira」which would decide Tanjiro’s fate, his mind was wandering(talking to himself「what is the shape of that cloud again? What is it called?」). He says he is fine either way since he is going to forget anyway.

Even so, when facing Master Kagaya Ubuyashiki, he is as reverent and shows courtesy as other「Hashiras」. He would flicks Tanjiro, who quarrels with Sanemi Shinazugawa and refuses to be dismissed, in the head with a pebbleas a punishment because Tanjiro「are not allowed to interrupt the Master」.

He tends to think only for himself and operates on logic alone. Anyone who gets in the way will be treated ruthlessly, sometimes he’s even willing to use his strength.
Muichiro insists that「Instead of wasting most time protecting one person, we should choose to protect more people」・「a Hashira’s time is more valuable than that of the rest」. He thinks calmly and rationally, but he is too blunt and has difficulty interacting with people. Tanjiro thinks his philosophy is 「right, but totally uncaring and cruel」.
However, it does not mean that he is egocentric or selfish. It is just Muichiro being acting on Demon Slayer Corps’ principal of 「protecting human lives from demons」. Even Tanjiro who acts on instincts never feels him acting in bad faiths. Although there is an aggressive side of him, Muichiro, as a demon slayer whose duty is to protect innocent people, has a strong sense of mission and justice. He never hesitates when it comes to the moment that he needs to step forward as a shield to protect the non-combatants. As young as fourteen he has already become a true Hashira.

Besides, according to his attendant Kasugai crow, he is the decedent of Sun Breathing. And his true strength is still unknown.

On the other hand, for some reason, Muichiro is suffering from memory loss, and a sequela of inability to recall the recent past.
During the Hashira Meeting, when asked how he considers about Tanjiro’s sanction, he claimed that there is no need for him to care as he would soon forget about the circumstance anyway.
Therefore, when it comes to Ubuyashiki, who consoles Muichiro and gives him confidence that there is no need to worry, he takes him as his spiritual pillar. And Muichiro is devoted to his position as the Demon Slayer Corps’ Hashira.
Sometimes, in his interaction with Tanjiro, Muichiro can act his age. His coldness might be a side effect of memory loss.
Also, as another side effect of memory loss, Muichiro uses 「boku」と「ore」 in a confusing way. His tone may suddenly turn vulgar and critical.

Ability

Contrary to his glamorous appearance, by pushing the limits of human body, Muichiro makes himself strongly-built enough to be a Hashira.
He is very talented and able to become a Hashira just two months after starting his demon slayer training. Besides, his diligence also ensures full utilization of ability.
He emphasizes effectiveness very much. Regarding training methods and sword techniques, he only adopts effective ones.

Equipment

The handhold of his Nichirin sword is green and the gold-rimmed handguard is in the shape of overlapped squares.
As a Hashira’s sword, the white blade is engraved four kanji characters meaning “DESTROY DEMONS”.
The swordsmith is Kanamori, but the original swordsmith is an old man named Tetsuido.
In Tetsuido’s eyes, Muichiro is not the demon slayer Hashira, but a child who has lost both his family and memory. He understands Muichiro’s situation and is worried about his future. When he realizes that there is not much time left for him, he hands his workbook to his successor Kanamori.
Muichiro once has his sword broken off in fighting Yoriichi Zeroshiki. Since then he is using one of the battle doll’s swords. However, after chapter 119, Muichiro gets a new Nichirin sword made by Kanamori who makes this sword following exactly the instructions as it is written in Tetsuido’s workbook.

Uniform

Muichiro wears loosely a standard Demon Slayer uniform that has a kanji character meaning “DESTROY” on the back. It is rare among Hashiras. He does wear gaiters. All in all, he dresses in a very simple way.
According to fanbook, Muichiro deliberately wears a loosely fitting uniform to keep some information (such as the arm length, configuration of his arms and joints, etc. ) from demons

Kasugai crow

Muichiro has a rarely seen female Kasugai crow with long eyelash.
This Kasugai crow adores her master Muichiro in a Monpa way.
She likes to brag to others that 「that Muichiro boy is a genius！！He is just not in the same dimension with you guys！！」. It is this Kasugai crow who tells Tanjiro that Muichiro is the decedent of Sun Breathing.
In her eyes, Tanjiro who is starting to talk about inheritance of memory is totally「unrealistic」. And Tanjiro retorts that a speaking bird is way unrealistic.
Tanjiro who acts on instincts says that 「（compared to Muichiro）this bird is totally malicious. she despises me」
She cannot get along with Tanjiro’s crow. She calls Tanjiro’s crow「nobody」, and Tanjiro’s crow retorts by calling her「ugly eyelash crow」.

History

The great genius swordsman Muichiro was from a modest background. He was born to a Somabito and his wife who lived in a distant mountain.
When he was ten, his mother caught a cold which developed into bronchitis and killed her. His father, who had gone to fetch medicinal herbs for his mother during a storm, ended up falling off the cliff and died too.
At the age of eleven, Muichiro lost his parents, and was left to stick it out together with his only family, his twin brother・Yuichiro.

Yuichiro and Muichiro look very much alike, but completely different from Muichiro, Yuichiro is cold and critical.
Yuichiro thinks that 「kindness is useless and helping others is meaningless」 and he harshly criticizes their parents. On the contrary, Muichiro like his father thinks that 「one should aim to do good for others if one wants good to be done for oneself」. Muichiro has a similar argument with Tanjiro in chapter 106. And the argument suddenly reminds him of a similar conflict with his brother (later, with this argument lingering in his head, he chooses to save Kotsetsu and begins to get his memory back).

In the following spring, Ubuyashiki’s wife・Amene visited them. She told the brothers that they were the 「decedents of the first Breathing」 and recruited them for Demon Slayer Corps. Yuichiro thought Amene 「must have an unknown scheme」and refused her.
Yuichiro would get ignited when Muichiro suggested that they should join Demon Slayer Corps. He retorted that Muichiro was just like their parents who died for their stubbornness and for not listening to his advice. He insisted that「only the chosen one was able to protect others」, and 「people like them were to die meaninglessly」. Gradually, the twins grew apart and stopped talking to each other. While Amane continued to visit the twins, Yuichiro chased her away each time and refused to join Demon Slayer Corps. Most sadly, the last conversation between the twins was a quarrel about Yuichiro’s chasing Amane away by splashing water on her on one of Amane’s visit.
（all other Hashiras volunteer to join Demon Slayer Corps. Joining at the invitation of Ubuyashiki’s is exceptional.）
In the following summer, a season when people started to leave their window open at night, a demon arrived at their cabin during the night and attacked the twins, resulting Yuichiro fatally wounded. As the Demon badgered them for their worthlessness, Muichiro lost himself in a rage and smashed the Demon with all the tools (log, stake, shear, rock,etc.) at his disposal. Eventually, by the sunlight, the demon withered into ash.
In the dying moments, Yuichiro was still praying to the heaven that「his kind-hearted brother should survive」. And before passing away, he told Muichiro that 「the word Mu in his name means infinite」. Amane and her daughters later arrived to heal Muichiro. Before their arrival, Muichiro was sitting still, watching maggots feeding on his brother’s rotten torso.
Muichiro lost his memories because of the physical and mental damage. He was even not able to recall a recent past.
He then was taken to Ubuyashiki Estate and joined Demon Slayer Corps. As it is mentioned above he quickly rose to the rank of a Hashira only two months later on. Muichiro lost his memories, but those pains were deeply implanted into his body. Driven by a boiling rage, he pushed the limits of human body to train himself. Even bandage and hematemesis never made him take a break. This diligence and determination, together with his talent made him a Hashira within two months.

After his memories returned, Muichiro thinks that he in the mental status of memory loss has behaved like Yuichiro. Judging from his early recollection that he once believed that he was the only child of the family; he probably has thought Yuichiro and himself were the same person.
The true Muichiro is gentle and would exert unlimited strength to help others. From this point of view, he is Tanjiro’s kin spirit (In manga chapter 118, Muichiro’s past and true personality became clear. And after his memories returned, he was even found out to have the same mark with Tanjiro. So many readers think that Muichiro is very much like a protagonist . )

After his memories returned, Muichiro still uses both「boku」and「ore」to refer to himself, but more reasonable. On the whole, his personality trait is then highlighted by the major characteristics from both himself and his brother.
Besides, after memory restoration, the author adds highlight in his pupils to underline the difference.

Muichiro’s father looked like Tanjiro and had similar 「red eyes」. So, there is a conjecture that the Kamado family in some way may have some connection with the Tokito Family. However, Tanjiro’s pupils are in the shape of a full sun, while Tokito father’s pupils are in the shape of a solar eclipse.

Digression

In the first edition of the official fanbook, Muichiro’s birthplace is Mount Odake, the same as Inosuke. Later, Koyoharu Gotouge, author of this manga made a public apology statement through the official twitter account of this manga, declaring that Muichiro’s birthplace in this fanbook was wrong. Together with the statement, Koyoharu Gotouge also posted an illustration. In the right half of this illustration, Muichiro and Inosuke bend their arms around each other’s shoulder, an impossible scenario never seen elsewhere, and Koyoharu Gotouge wrote a mysterious onomatopoeia「ZONBIPA」on the lower right corner, which ignited a spark of interest in fans.

Since then, more and more manga fans start to use the word ZONBIPA to address the Muichiro and Inosuke duo.

Related illustration

！！Spoiler alert. The following contents are not included in Tankobon volumes！！

In chapter 165 of Kimetsu manga, it is disclosed that Muichiro is the decedent of Upper Moon One Kokushibou.
It is also disclosed that the same as Kotito brothers, Kobushibou（Michikatsu Tsugikuni）and Yoriichi Tsugikuni are twin brothers (Yoriichi Tsugikuni has made the Kamado family promise to pass down the Dance of the Fire God and hanafuda earrings in every generation).
Since Yoriichi does not have any child, Muichiro becomes the last and successor of the Sun Breathing style.